1. Field of the Invention
The present invention relates in general to an engine cooling system of the type wherein the coolant is boiled, so as to make use of the latent heat of vaporization thereof, and the coolant vapor used as a vehicle for removing heat from the engine, and more particularly to an improved coolant level sensor arrangement therefor.
2. Description of the Prior Art
Hitherto, a so-called "boiling liquid cooling system" (viz., evaporative cooling system) has been proposed for achieving cooling of an internal combustion engine. This type of cooling system basically features an arrangement wherein a liquid coolant (for example, water or a mixture of water and antifreeze or the like) in the coolant jacket of the engine is permitted to boil and the gaseous coolant thus provided is passed out to an air-cooled heat exchanger or radiator where the gaseous coolant is cooled or liquefied and then recirculated back into the coolant jacket of the engine. Due to the effective heat exchange achieved between the gaseous coolant in the radiator and the atmosphere surrounding the radiator, the cooling system exhibits a very high performance.
As will become apparent hereinafter, some of such cooling systems are provided with a coolant level sensor for detecting the level of liquid coolant in the coolant jacket of the engine. With the signals from the sensor, the amount of the coolant in the coolant jacket is so controlled as to constantly cover the highly heated zones of the jacket under operation of the engine.
However, due to the bumping and frothing of the coolant which accompanies an inevitable vigorous boiling in such highly heated zones, the level detection by such level sensor is often erroneous thereby deteriorating the performance of the cooling system.